Certain latching systems, or any other type of mechanical engagement system, typically require a way to determine when full engagement has been achieved between two mechanical parts. These mechanical parts may both be movable or one can remain stationary relative to the other. One example of such systems requiring accurate and dependable engagement sensing schemes are vehicle restraint systems.
Vehicles are provided with seat restraints systems such as seat belts in order to restrain occupants in the seat. The proper engagement and operation of the seat belt ensures the safety of a driver and his or her occupants.
Seat belts often incorporate sensors that provide data to other vehicle restraint vehicle systems such as airbags. Deployment of an airbag may partially depend on the information supplied by the sensor in the seat belt, such as a sensor may determine the presence of an occupant on the seat. In some applications, it may be desirable to suppress the deployment of an air bag. For example, if an airbag corresponding to an unoccupied seat deploys, an unnecessary repair expense occurs. In addition, such sensors can also be used to indicate that the seat belt is properly tightened and properly engaged or latched for proper reliance thereon. Determination of a latched, or unlatched, condition of the belt may also be used to determine how the airbag should be deployed. A latched condition will deploy the airbag softly, while still protecting against injury due to impact. An unlatched condition will deploy the airbag at a much harder and quicker pace since this is an indication of an occupant not wearing a safety belt.
Most of the sensors employed today as latch engagement detectors are of a mechanical switch type. These mechanical switches involve at least two pieces that are in and out of continuous frictional contact, thus producing wear and misalignment with aging. Wear and misalignment between the mechanical pieces will eventually result in a latch detection failure.
Accordingly, there is a need for a seat belt latch sensor assembly that minimizes or eliminates one or more of the problems set forth above.